Gutierrezia microcephala |
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small-head snakeweed, sticky snakeweed, threadleaf snakeweed |
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Habit | Subshrubs, 20–140 cm. |
Stems | glabrous or minutely hispidulous. |
Leaves | basal and proximal absent at flowering; cauline blades 1-nerved, linear or filiform to narrowly oblanceolate or lanceolate, 0.5–2.2(–4) mm wide, little reduced distally. |
Involucres | cylindric, 1–1.5 mm diam. |
Ray florets | 1(–2; each enclosed by conduplicate inner phyllary); corollas yellow, (1.5–)2–3.5 mm. |
Disc florets | 1, sometimes 2 (functionally staminate; corollas broadly obdeltate-funnelform, throats widely flaring, lobes 1/3 corolla lengths, recurved-coiling). |
Heads | (2–6, sessile to subsessile, in compact glomerules) in flat-topped arrays. |
Cypselae | 1–1.8(–2.5) mm, faces densely strigoso-sericeous; pappi (rays, readily falling) of 1 series of narrowly lanceolate-oblong scales. |
Phyllary | apices flat. |
2n | = 8, 16, 24, 32. |
Gutierrezia microcephala |
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Phenology | Flowering (Jun–)Jul–Dec(–Feb). |
Habitat | Grasslands, chaparral, oak or oak-pine woodlands, usually over gravelly or rocky limestone or gypsum substrates, dunes |
Elevation | 800–2500 m (2600–8200 ft) |
Distribution |
AZ; CA; CO; NM; NV; TX; UT; Mexico (Baja California, Chihuahua, Coahuila, Durango, Nuevo León, San Luis Potosí, Sonora, Tamaulipas, Veracruz, Zacatecas)
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Discussion | Gutierrezia microcephala is recognized by its perennial habit and its small, tightly clustered heads, each with 4–8 phyllaries and 1(–2) ray and disc florets. Each ray floret is enclosed by a conduplicate inner phyllary. Forms of G. sarothrae with few florets in each head can be distinguished by their bisexual and fertile disc florets and tubular-funnelform disc corollas. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 20, p. 92. |
Parent taxa | Asteraceae > tribe Astereae > Gutierrezia |
Sibling taxa | |
Synonyms | Brachyris microcephala, G. sarothrae var. microcephala, Xanthocephalum microcephalum |
Name authority | (de Candolle) A. Gray: Mem. Amer. Acad. Arts, n. s. 4: 74. (1849) |
Web links |